This invention relates to a combined oil and gas burner designed to achieve low levels of nitrogen oxides, commonly known as NOx, in the combustion products of the burner.
NOx emissions from burners used in power plants and other industrial applications are a substantial source of air pollution and the design of burners which will produce low NOx emissions has been the subject of substantial research and development. Many techniques employed to reduce NOx emissions are designed to reduce the temperature in the combustion zone of the burner, because reduced temperature is conducive to burning with low NOx emissions. Lower combustion temperatures and, therefore, lower NOx emissions are achieved in prior systems, by introducing combustion products into the combustion zone, such as by recirculating flue gas into the combustion zone or by providing multi-stage burning wherein preburning is caused to take place upstream of the main burner flame. Other techniques involve using primary air with limited oxygen supply to establish a primary burning zone and introducing secondary air for a secondary flame zone downstream from the primary flame.